Application of electron diffraction to rapid structural elucidation of crude reaction products

The explicit confirmation of the identity of desired or side products of a chemical reaction often requires lengthy or iterative purification protocols, combined with multiple analytical procedures that could be restricted by the available sample quantity and purity, or might provide only qualitative information on the chemical composition. Product mixtures with overlapping spectroscopic signals, low solubility, reactivity in solution, poor crystallinity, and multiple sample preparation steps could pose further challenges and currently stand in the way of full automation of product characterization. Being capable of rapidly providing structural details down to atomic scale resolution from nanosized crystalline samples, three-dimensional electron diffraction (3D ED) (microcrystal electron diffraction) effectively overcomes several of these obstacles. Here, we demonstrate the potential for the application of 3D ED in the efficient and rapid characterization of reaction products that are difficult to characterize. Furthermore, the technology utilized in this paper comes with the benefits of reducing the carbon footprint of a synthesis procedure, eliminating redundant steps needed for common characterization methods, and providing a shortcut for characterization without increased costs. We suggest that, based on the speed and minimal sample requirements demonstrated here, coupling 3D ED/MicroED with automated synthetic workflows could help accelerate future drug discovery efforts.